Malbaby Posted June 8, 2023 Report Share Posted June 8, 2023 (edited) Although my car is TR4, and does not have the same weight distribution... IMHO....I would aim for so called "standard" springs of around 310 lbs/in. One problem is that the retail suppliers cannot give you accurate compression rates. They rely on their wholesalers for information.. Finding someone local to where I live that can accurately test springs has been impossible. One retailer can have a spring they say is rated at 320, and another will offer the same spring rating... ie..same wire diameter and height that is rated the same, but have a different number of free/active coils..eg..6 instead of 7. Assuming that the wire quality is the same [difficult to know], then the two springs cannot possibly have the same compression rate...The 7 free coils spring can have a lower rating of of up to 40lbs....I accept that the wire steel can differ in strength, so the bottom line on this can only be from accurate compression measurement. I have been experimenting with different rating front springs for some time to try and achieve a comfortable [for me] ride at a ride height that I was happy with, is ongoing. My current setup is Rimmers "standard" springs without any packers. Ride comfort is OK, but I would prefer softer. Ride height is also higher than I would like.....Could be ideal for the heavier TR6. Have now decided to have a pair custom made. Edited June 8, 2023 by Malbaby Quote Link to post Share on other sites
Z320 Posted June 8, 2023 Report Share Posted June 8, 2023 10 years ago I made this with a friend Quote Link to post Share on other sites
BaulyCars Posted June 8, 2023 Author Report Share Posted June 8, 2023 Very nice. You'd think good retailers would have something similar (or at least have verified info from suppliers). Also would be nice if the springs were stamped/etched with their rating. Quote Link to post Share on other sites
BaulyCars Posted June 8, 2023 Author Report Share Posted June 8, 2023 5 hours ago, Malbaby said: Although my car is TR4, and does not have the same weight distribution... IMHO....I would aim for so called "standard" springs of around 310 lbs/in. One problem is that the retail suppliers cannot give you accurate compression rates. They rely on their wholesalers for information.. Finding someone local to where I live that can accurately test springs has been impossible. One retailer can have a spring they say is rated at 320, and another will offer the same spring rating... ie..same wire diameter and height that is rated the same, but have a different number of free/active coils..eg..6 instead of 7. Assuming that the wire quality is the same [difficult to know], then the two springs cannot possibly have the same compression rate...The 7 free coils spring can have a lower rating of of up to 40lbs....I accept that the wire steel can differ in strength, so the bottom line on this can only be from accurate compression measurement. I have been experimenting with different rating front springs for some time to try and achieve a comfortable [for me] ride at a ride height that I was happy with, is ongoing. My current setup is Rimmers "standard" springs without any packers. Ride comfort is OK, but I would prefer softer. Ride height is also higher than I would like.....Could be ideal for the heavier TR6. Have now decided to have a pair custom made. Seems fundamentally difficult to get an ideal balance between spring rate, ride height and damper travel. I assume if do a custom softer spring with the right height you're after you'll still have damper travel issues. Quote Link to post Share on other sites
Z320 Posted June 8, 2023 Report Share Posted June 8, 2023 On the photo we tested the red Bastuck spring, which Bastuck declares made from the German producer „H+R“ - but don’t tell its rate. We tested original springs and others too and got a friendly offer from H+R to test two of them and compare with our results. Their answer: our results are relatively correct (to compare 2 springs), but too high! Likely reason: we made a calculation pressure x surface = force. But the force (pressure) to start moving the hydraulic rod through the lip seal („brake free forces“) is higher than the pressure in a closed hydraulic sensor. Like retorque bolts without opening them one flat before (to get a sliding movement) Quote Link to post Share on other sites
Z320 Posted June 8, 2023 Report Share Posted June 8, 2023 We needed a sensor below the spring good for 600 kg but this was too expensive Quote Link to post Share on other sites
BaulyCars Posted June 8, 2023 Author Report Share Posted June 8, 2023 If I'm reading that correctly both springs well matched. Linear too. Progressive springs would also be a nice way to solve some of the spring rate vs rideheight issues - that might be worth looking at @Malbaby if you do go custom, being softer in the initial travel range. Quote Link to post Share on other sites
Z320 Posted June 8, 2023 Report Share Posted June 8, 2023 In short words: forget progressive springs on a road car, please. That works on a motocross cycle, farming vehicle of offroad car with huge way of travel, not on +/- max 20 mm way if travel on a TR. Quote Link to post Share on other sites
BaulyCars Posted June 8, 2023 Author Report Share Posted June 8, 2023 I thought progressive springs were available that seemed quite short (similar in length to TR springs maybe), this sort of thing below. Admittedly haven't looked into it in any detail. Quote Link to post Share on other sites
Z320 Posted June 8, 2023 Report Share Posted June 8, 2023 If you can explain how this works…. Quote Link to post Share on other sites
BaulyCars Posted June 8, 2023 Author Report Share Posted June 8, 2023 The spring rate varies through the compression stroke due to the different coil spacing (and/or different coil diameter, the example seems to have a bit of both). But I don't know if anyone makes one that's roughly the right dimensions for a TR (or the right spring rates). Quote Link to post Share on other sites
Z320 Posted June 8, 2023 Report Share Posted June 8, 2023 Theoretically, practically the soft part has to be fully compressed to get to the benefit of the stiff part. As long both parts act like a spring softer than each part of the unit. For this you don’t have enough way of travel on a road car, also farming vehicles do this different with a coil in coil. The springs from your photo are only wish and hope Quote Link to post Share on other sites
Z320 Posted June 8, 2023 Report Share Posted June 8, 2023 (edited) The formula for springs in a row is 1/r = 1/r1 + 1/ r2 + 1/rn The result is softer than each single of them - until the first one is fully compressed Edited June 8, 2023 by Z320 Quote Link to post Share on other sites
BaulyCars Posted June 8, 2023 Author Report Share Posted June 8, 2023 Eibach do this set-up for road/race (softest to the left, middle is soft/hard, right is linear) - still too long though.... H&R do something similar. Quote Link to post Share on other sites
Malbaby Posted June 8, 2023 Report Share Posted June 8, 2023 (edited) Like Marco, I do not think that there is enough height for progressive springs, as in the Eibach pics to be effective. The only way that I can see to obtain a progressive spring rate is to have springs custom made with the free/active coils gradually increasing in number. Whether that is feasible or not, I do not know. There must be a computer program somewhere that could do the design regarding wire diameter, active coils and variable pitch. Edited June 8, 2023 by Malbaby Quote Link to post Share on other sites
Z320 Posted June 9, 2023 Report Share Posted June 9, 2023 Excuse me for me lack of talent to explain better, please. If you believe this works, please go that way. Ciao, Marco Quote Link to post Share on other sites
BaulyCars Posted June 9, 2023 Author Report Share Posted June 9, 2023 10 hours ago, Malbaby said: Like Marco, I do not think that there is enough height for progressive springs, as in the Eibach pics to be effective. The only way that I can see to obtain a progressive spring rate is to have springs custom made with the free/active coils gradually increasing in number. Whether that is feasible or not, I do not know. There must be a computer program somewhere that could do the design regarding wire diameter, active coils and variable pitch. QA1 have these on their website as perhaps a better example, showing a 225/475 combination - 10 inch would be about stock height on a TR6. I'll keep looking! Quote Link to post Share on other sites
Z320 Posted June 9, 2023 Report Share Posted June 9, 2023 (edited) Help please! Is there anybody out there, apart from Melcolm, understanding what I explained? Edited June 9, 2023 by Z320 Quote Link to post Share on other sites
Chilliman Posted June 9, 2023 Report Share Posted June 9, 2023 20 minutes ago, Z320 said: Is there anybody out there, apart from Melcolm, understanding what I explained? Yes, you are quite clear Marco and I agree - in a nutshell the travel available on the TR is insufficient to make a variable rate spring a viable alternative. There are a vast array of spring rates & sizes already available - I've swapped the front of my green 4 three times this year to arrive at what I feel is a good set up for my needs in competition. But, that was all done as a part of a considered suspension upgrade involving all the springs/dampers & anti roll bars. Not exactly built for comfort! Quote Link to post Share on other sites
BaulyCars Posted June 9, 2023 Author Report Share Posted June 9, 2023 50 minutes ago, Z320 said: Help please! Is there anybody out there, apart from Melcolm, understanding what I explained? I understand it, the damper/spring travel is small - how to solve that? Quote Link to post Share on other sites
Hamish Posted June 9, 2023 Report Share Posted June 9, 2023 39 minutes ago, Chilliman said: Yes, you are quite clear Marco and I agree - in a nutshell the travel available on the TR is insufficient to make a variable rate spring a viable alternative. There are a vast array of spring rates & sizes already available - I've swapped the front of my green 4 three times this year to arrive at what I feel is a good set up for my needs in competition. But, that was all done as a part of a considered suspension upgrade involving all the springs/dampers & anti roll bars. Not exactly built for comfort! Me too on my 3a to lower the car for comp. I went too low to be practical so have reverted back to where I was last year !! But with really stiff front springs you don’t have to worry about suspension travel!! Quote Link to post Share on other sites
Z320 Posted June 9, 2023 Report Share Posted June 9, 2023 59 minutes ago, BaulyCars said: I understand it, the damper/spring travel is small - how to solve that? The answer is already in that post Quote Link to post Share on other sites
BaulyCars Posted June 9, 2023 Author Report Share Posted June 9, 2023 8 minutes ago, Z320 said: The answer is already in that post I thought you might say that - but for the issue of wanting a softer spring but not the rideheight. If I were to go to the effort of modifying the brackets as per yours, what if alternatively the spring pan were revised to lower the spring support (and the original damper brackets). Could that allow a longer, softer spring (maybe the original spring), but lower the rideheight and also preserve the damper travel? Quote Link to post Share on other sites
Z320 Posted June 9, 2023 Report Share Posted June 9, 2023 (edited) On 6/8/2023 at 9:23 AM, BaulyCars said: If I'm reading that correctly both springs well matched. Linear too. Progressive springs would also be a nice way to solve some of the spring rate vs rideheight issues - that might be worth looking at @Malbaby if you do go custom, being softer in the initial travel range. This was you question and I try to answer it better. This is all my opionion, anybody can come to a different conclusion. The issue with the progressive springs is - both parts of the spring react and are compressed before the spring changes its character. Guess the spring is in the car, car on the wheels - and the softer part of the spring with 5 loops (photo above) needs 12 mm way of travel to be fully compressed (the loops start with only a 3 mm gap to each other), while the stronger part also is compressed for example 7 mm. This is very narrow with low tolerance and anyway is already 19 mm way of travel (while I notice we have maximum 20 mm on a TR). From this point only the stronger part of the spring rules and the spring changes from soft to stronger. On my neighbour's "Unimog" this works different with a "spring in a spring" (earlier that post) First only the outside spring is compressed, the inside spring doesn't act. And after a way of travel of I guess 80 mm (?) the inside spring touches the spring pan and supports the outside spring. The formula for springs next to each other is r = r1 + r2 + .... rn. Very simple and easy to calculate. On the TR4A-TR6 the same happens when the shock absorber is pressed down to the bump "stop". "The stop" is no stop but an elastic element "about like" a spring and makes the hole construction progressive. When I changed to shorter and stronger "Bastuck" springs 10 (?) years ago this was to stiff for my taste - and after only a few millimeters way ot travel the shock absorbers have been fully compressed down on the elsatic bump stop. This was very "progressive" and a real pain. I cut the rubbers 20 mm shorter and this gave me more way the point to be progressive. This was where the story started for me to have a closer look. I hope this helps at the moment. Ciao, Marco Edited June 9, 2023 by Z320 Quote Link to post Share on other sites
Malbaby Posted June 9, 2023 Report Share Posted June 9, 2023 (edited) 14 hours ago, BaulyCars said: QA1 have these on their website as perhaps a better example, showing a 225/475 combination - 10 inch would be about stock height on a TR6. I'll keep looking! 14 hours ago, BaulyCars said: Yes, I can see that these could to be a good option providing the upper tower and lower spring pan were modified to accommodate the smaller ID springs . One problem is that normally the tension on the spring varies from the inner side of the car to the outside. Ride height is the determining factor..[how often have you seen springs removed from a car and they are slightly concave on one side] The lower spring pan would have to be modified so that at the car's chosen ride height, the top surface of the coil is exactly parallel to the bottom. The next consideration is how much clearance there is between the shock absorber and the inner surface of the smaller ID spring through it's travel range.. Hopefully someone will experiment with the proposed set up and do an appraisal. Edited June 9, 2023 by Malbaby Quote Link to post Share on other sites
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